1. Field of the Invention
The present invention is broadly concerned with a method for the preparation of masa flour which eliminates many of the costly, time-consuming, pollution causing steps conventionally carried out in the preparation of such flours. More particularly, it is concerned with a masa preparation method wherein debranned, moisturized and partially cooked grain (e.g., corn or wheat) is subjected to a flash dehydration process in order to quickly dehydrate the debranned grain, which can then be milled into an acceptable masa flour. In the flash dehydration, high velocity hot air currents having a temperature of from about 600.degree.-1000.degree. F. are employed for the rapid grain dehydration.
2. Description of the Prior Art
Masa flour, typically made using food grade corn or wheat, is produced in tremendous quantities in the United States and around the world. Such flour is used to fabricate such familiar products as tortilla chips and taco shells.
Despite the demand for masa flour, for the most part it is prepared using very old and time honored techniques. In the first step, whole kernel corn is cooked in a mixture of water and 1% lime up to a temperature of 175.degree.-205.degree. F., depending upon the hardness of the starting corn and other factors. The corn is then allowed to steep in the lime water for a period of 8-12 hours, in order to allow the lime to penetrate, loosen and partially dissolve the pericarp or bran fraction of the corn.
The steeped corn is then passed through a corn washer, comprising a perforated, rotatable cylinder equipped with internal water jets, in order to complete the removal of bran and to reduce the pH of the corn to about 6.5-7.5.
In the next step, the washed, debranned corn is passed through a stone grinder to mill the corn to a desired particle size and thus complete the flour preparation. The flour may then be appropriately dried for storage, sale and use, or used directly. Masa products are typically prepared by forming a 1:1 (w/w) dough of the masa flour and water, followed by forming the dough through an extruder or other like device, followed with subsequent drying, equilibrating and frying. The final fried masa products are then cooled, salted and packaged.
The conventional masa flour preparation technique presents a number of serious difficulties. First of all, the time required to process the flour is considerable, owing principally to the need for extended steeping. Secondly, the established method has serious ecological consequences, in that the steeping water contains considerable quantities of objectionable dissolved pericarp and soluble starches. Removal of these organic substances from the steeping water is an expensive proposition for masa flour producers, and some flour plants are reported to incur expenses of many thousand dollars per month simply to remove these pollutants from their process streams.
U.S. Pat. No. 5,176,931 represents a new approach to masa flour production. This patent describes a process wherein, after alkali metal hydroxide treatment of grain, the grain is subjected to near infrared radiation and subsequent milling. By this means, process times are significantly reduced as compared with the traditional process. However, the technique described in the '931 patent can be difficult to control in commercial scale production, particularly during the near IR treatment step.